<!DOCTYPE html>
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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
var findMagicIndex = function(nums) {
    for( var i = 0 ; i<nums.length ; i++ ){
        if( nums[i] == i ){
            return i
        }
    }
    return -1
};

var nums = [0,2,3,4,5]
console.log(findMagicIndex(nums))
    </script>
</body>
</html>